This project is part of a multicenter collaborative study to test the hypothesis that high frequency ventilation is more effective in treatment of pulmonary interstitial emphysema as compared to conventional ventilation using a randomized model stratified by severity of pulmonary interstitial emphysema and birthweight in newborns > 750 grans. We will study hemodynamic impact of HFV as compared to CV by using noninvasive Doppler and echocardiographic techniques to determine SOT, MF, and effect on PDA.